QRP Voice Powered Transmitters - CW and Speech!

[Phil]

My primary school had a new canteen and hall with a 200 foot iron fence around it in a U-shape. We used to send coded messages from one end to the other by tapping the rail with keys. Mind you, battery-free transmitters - I'm still trying to grasp it. I particularly like the way the full-wave rectification doubles the voice pitch. Move over, chipmunks!

Next challenge - 100% battery-free radio DX contest?

Phil M1GWZ


On 15 Mar 2013, at 02:23, Joseph Bento wrote:

> Richard,
> 
> I was about that age when I discovered that the ear pieces from a Western Electric 500 telephone needed no power source to produce a 'telephone'.  I had two ear pieces and connected them together.  I then reconnected them via a 100 foot extension cord.  I had made a sound-powered telephone, and I didn't even (yet) know what that was.
> 
> Joe, N6DGY
> 
> 
> On 3/14/2013 7:57 PM, Richard O'Neill wrote:
>> On 3/14/2013 7:48 PM, Phil wrote:
>> 
>> …and into the tin.
>> 
>> It was around the forth or fifth grade when I discovered one could make a phone with paper cups and kite string. As I recall it worked well over a hundred feet. Today, communicating by radio over 100 miles by voice and 1300 miles by code with no energy source other than the spoken word seems almost unbelievable. I just gotta build me one of these. I presume it's covered by part 15 rules. ;-)
>> 
>> Richard
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> 
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